For omnivorous brown bears, ants can seasonally constitute an important category of food with high nutritional value. A former dietary study conducted in Estonia revealed that the energy gained from animal and plant food was roughly equal, whereas the contribution of ants was almost 15%. Here, using the same dataset, we analyzed ant consumption by brown bears in Estonia at a greater taxonomic resolution and evaluated the preferences of brown bears towards different ant species by measuring the availability (biomass and mound density) of ants in the study area. Among the 18 species and five groups of ants in bear scats, members of the genera Lasius and Formica were the most abundantly consumed ant groups, considering both the volume and frequency of occurrence. Among the species we detected, Lasius niger and Formica polyctena dominated. However, these were not the favorite ant taxa for bears, that highly preferred Camponotus ants and avoided Myrmica ants.
In addition, a new species (Camponotus fallax) for Estonian ant fauna was discovered, providing an example of how studies on mammal food habits can reveal elusive insect species that have remained undiscovered with traditional survey methods. The general pattern of the brown bear myrmecophagy in Europe is examined to place our results into a broader context.